Re: [Patch] sext_hwi: Avoid left shift of negative value undefined behaviour

[Jeff Law]

On 08/06/2015 04:25 AM, Mikael Morin wrote:
Hello,
this avoids an error found with bootstrap-ubsan.
Regression tested on x86_64-unknown-linux-gnu.  OK for trunk?

Mikael


noub_sext.CL


2015-08-05  Mikael Morin<mik...@gcc.gnu.org>

        * hwint.h (sext_hwi): Rewrite without undefined behaviour on
        negative SRC.
OK.  Hopefully most of the time the precision is known at compile-time 
which would allow for optimization of the resulting code back to the 
pair-of-shifts form by combine.




jeff